A. Field of the Invention
The present invention relates to articles for temporary attachment to the corners of flat, rectangularly-shaped frames for holding pictures, diplomas. mirrors and other flat objects to protect the frames and objects from impact damage during shipment and storage, and to machines and methods for making such articles. More particularly, the invention relates to novel slip-on corner protectors installable without tools on the corners of frames, and a novel machine and method for making slip-on corner protectors.
B. Description of Background Art
Picture frames for holding and displaying paintings, photographs, diplomas, certificates and similar flat articles are manufactured in prodigious quantities worldwide. Although picture frames vary in shape and construction details, most frames have a rectangular plan view shape, consisting essentially of four straight channel members or moldings. Each member has an inner channel that intersects channels of adjacent members at a ninety degree angle and four such channel members are fastened together to form a rectangular ring-shaped frame. The channels or recesses in the moldings together to form a rectangular ring-shaped space for receiving the outer peripheral edges of a rectangularly-shaped flat display piece such as a photograph or painting, and optionally, additional flat members such as a backing panel, mat and protective cover glass.
Picture frames of the type described above are made from a variety of materials including, wood, metal and plastic. Whatever material the frame is made of, the geometry of a rectangular picture frame dictates that it have four peripheral members of generally uniform thickness which are joined at each other at forty-five degree miter angles to form ninety-degree corners. These corners are sharp, and are therefore highly subject to breakage, denting or occupied, are fitted with some sort of corner protector during shipment. Such corner protectors are usually made of a relatively inexpensive recyclable material such as cardboard or polystyrene foam. Typical corner protectors of this type are disclosed in U.S. Pat. Nos. 3,955,677, 4,598,825, and 5,447,233. Other patents, related to protecting corners of objects during shipping include U.S. Pat. No. 4,407,898. Also, U.S. Pat. No. 5,255,458 discloses a three-dimensional picture corner and U.S. Pat. No. 4,787,553 discloses a corner fastening device.
In addition to the above-referenced patents related to corner protectors and the like, a variety of machines for bending sheet metal or cardboard of the type used for corner protectors have been disclosed in the following U.S. Pat. Nos. 4,132,102, 4,585,432, 4,713,957, 4,857,038, 4,956,961, and 5,184,998.
None of the aforementioned references disclose a machine for automatically attaching corner protectors to picture frames. Accordingly, the task of attaching corner protectors to picture frames was formerly labor intensive and time consuming. In response to those limitations of the prior art, the present inventor disclosed an automatic Method and Apparatus For Attaching Corner Protectors to Picture Frames, in U.S. Pat. No. 6,018,934. In that patent, the present inventor disclosed a method and apparatus for installing covers to protect picture frame corners from damage during shipment, utilizing thin cardboard pre-forms having symmetric, left and right-hand, right-triangular coverflaps joined at vertical sides thereof to opposite vertical sides of a vertically elongated, rectangular spine flap, the left-hand triangular cover flap having depending downwardly from its base a horizontally elongated rectangular side cover slap, and depending downwardly from the lower lateral edge of the side cover flap a trapezoidally-shaped securement flap. The pre-form is positioned below a picture frame corner, with intersecting side members of the frame vertically aligned with the sides of the left-hand right-triangular coverflap, which serves as a lower face coverflap. The apparatus includes folder mechanisms including flap folder arms which are retractable into recesses provided in a work table, and which are extendible and rotatable to thereby bend the side cover flap and securement flap into a vertical position adjacent a first side of the frame cover and perpendicularly inwardly to overlie the first frame member, bend the spine flap and right-hand triangular cover flap into a vertical position adjacent the second frame member, and bend the right-hand triangular flap perpendicularly inwards from the spine flap to overlie the second and first frame members. An automatic staple gun then inserts a staple downwardly through the right-triangular cover flap in the securement flap and left-hand frame member, securing the corner protector in a folded disposition over the frame corner.
In U.S. Pat. No. 6,418,700, the present inventor disclosed an Automatic Tandem Corner Protector Attachment Method And Apparatus For Picture Frames And The Like, which provided a machine and method similar to those disclosed in the present inventor's U.S. Pat. No. 6,018,934, but provided a capability for simultaneously attaching corner protectors to two corners, thus effectively doubling the through-put or production rate of corner-protected frames.
Also, in U.S. Patent application publication No. US2003/0029552A1, the present inventor further advanced the art of picture frame corner protection by disclosing a Method And Apparatus For Adhesively Bonding Corner Protectors Onto Picture Frames And The Like, in which corner protectors were adhesively bonded to frame corners, and thus could be used on frames made of metal, plastic or any other material, as well as wood, without requiring the insertion of fastener staples into the frame.
The present invention was conceived of to provide a novel slip-on corner protector that could be quickly and easily attached to corners of a picture frame or the like, without requiring the use of any fasteners, tools, or adhesive, and a novel machine and method for manufacturing the slip-on cover protectors.